C|A discourse on 
the Detached Lever 
Escapement 


TS 545 
. H62 
Copy 1 




CHAS. T. HIGGINBOTHAM Con- 

suiting Superintendent SOUTH BEND 
WATCH COMPANY South Bend, Indiana 

4 


COMPLIMENTS OF 
SOUTH BEIKD WATCH 
COMPANY 













CHARLES T. HIGGINBOTHAM 

Mr. Higginbotham probably has a more thor¬ 
ough and broader experience in the science of 
making high-grade watches than any other man 
in the United States. 

Although sixty-five years of age, he takes an 
active part in all matters that concern the pro¬ 
duction of a movement that is gaining a reputa¬ 
tion as a most accurate and durable timepiece— 
the South Bend. 








A DISCOURSE. 

ON 

THE. DE.TACHE.D LE.VE.R 
E.SCAPEME.NT 



By 

CHARLES T. HIGGINBOTHAM 


Consulting Superintendent 
South Bend Watc-h Company 
South Bend, Indiana 




-rs $4-5 

( H k' 1 ' 



This little booklet contains the sec¬ 
ond of a series of lectures delivered by 
Mr. Higginbotham before various Con¬ 
ventions of the Retail Jewelers ’ dissocia¬ 
tions, and is passed to you, feeling it 
might be of interest. 




JbM-' 

(F. 

- iltfi 






THE DETACHED LEVER 
ESCAPEMENT. 


The office of a watch escapemenc is to 
transform the rotary motion of the train 
wheels. into the vibratory motion of the 
balance. That escapement which performs 
this office with the nearesc approach to 
uniformity and the least loss of power is 
best for tjiie purpose. The chronometer es¬ 
capement,^ without doubt, accomplishes 
this more fully than any other. It has, 
however, one serious objection when ap¬ 
plied to watches; namely, setting. This 
is to say, there is inseparable from it what 
is known as a dead point. The escape 
wheel delivers direct impulse to the bal¬ 
ance at alternate vibrations thac is, while 
the balance is making its excursion in one 
direction, its return excursion being made 
without receiving any impulse; hence 
there is a point where, if brought to a 
rest, neither the tension of the hairspring 
nor the force of the wheel can act, which 
is what is known as the dead point, and 
should some sudden jar arrest its motion at 
this point the time piece would stop. 

In the detached lever escapement when 
properly adjusted this condition does not 



exist. There is, however, considerable loss 
of power in communicating vibration to 
the balance by means of this escapement. 

Cause of the Loss of Power. 

Of the amount of force communicated by 
the train to the escape wheel more than 
1-3 is lost before it reaches the balance, 
even under the most favorable conditions. 
This may seem an extravagant statement 
but a brief review of the prevailing condi¬ 
tions in a lever escapement will demon¬ 
strate that it is by no means an over esti¬ 
mate. An escape wheel having 15 teeth de¬ 
livers 30 impulses to the fork during each 
revolution. Dividing 360 degrees by 30 we 
have 12 degrees as the arc of a circle 
through which the wheel passes at each 
impulse. Of this amount 10 degrees is 
active impulse. That is, the portion of the 
arc during which the wheel tooth and pal¬ 
let remain in contact The remaining 2 
degrees is taken up by drop. During the 
drop the wheel tooth simply passes through 
space without delivering any impulse hence 
it must be considered a loss of power. The 
loss amounts in this case to 1-6. The lock 
and slide take up from 1 V 2 co 2 degrees 
out of a total oscillation of 10 degrees of 
the fork. This is approximately 1-5 loss. 
In addition to this a slight reverse motion 
of the entire train takes place in the acc 
of unlocking. The mainspring is actually 

6 


re-wound to a slight extent The necessary 
freedom between the jewel pin and fork 
slot occasions another slight loss and the 
same is true of the side shake in the pallet 
arbor holes. Finally a serious loss occurs 
from the impact of the roller pin and fork. 

Lffect of Impact. 

At the instant of contact the balance has 
attained its maximum velocity and starts 
the fork and pallet from a dead rest into 
motion. In doing this it is obliged to over¬ 
come the inertia of these parts, not by a 
gradual pressure, but by a sudden blow. 
This loss is very great in proportion to 
the amount of metal contained in fork and 

pallets. The impact of the roller pin 
against the side of the fork slot in over¬ 
coming this inertia converts a portion of 
the force into heat. The heat is, of course, 
infinitesimal but nevertheless it is develop¬ 
ed just as surely as heat is developed in a 
rifle ball when fired point blank against a 
stone wall. It is a well known fact that 
the rifle ball becomes so hot that it cannot 
be handled. This heat is not produced by 
the burning powder but is the result of its 
sudden stoppage. A homely illustration will 
answer to show the condition prevailing in 
a watch. If we place a brick upon a 
table we can easily push it along with the 
pressure of a finger but if we attempt to do 
so wich a blow of the fist it will be at the 


7 


expense of lascerateri Knuckles. In view of 
the facts above stated it will be seen that 
in placing- the loss from all combined 
causes at 1-3 we are well within the limits; 
indeed % would in all probability be near¬ 
er the mark. It is evident cherefore that 
the importance of a correctly designed and 
properly adjusted escapement can hardly 
be over-estimated. It is our purpose in 
this little pamphlet to give instructions to 
our friends, the watch repairers, whereby 
the principal defects commonly found in 
escapements may be readily located and 
corrected 

Technical Names of Parts. 

Inasmuch as more than one name is of¬ 
ten used to designate the same part we 
have made figure 4 to represent an escape¬ 
ment the different parts of which are let¬ 
tered; the letters referring to the follow¬ 
ing list: — (A) che escape wheel. (B) the 
pallet steels. (C) the receiving pallet stone 
(D) the discharging pallet stone. (E) the 
fork. (F) the guardi-pin. (G) the roller 
(H) the roller pan. (II) the bankings. 

THE ESCAPE WHEEL. A:—(a) the 
escape wheel tooth, (b) the impulse face 
(c) the locking face, (d) the locking cor¬ 
ner. (e) the releasing corner. 

THE PALLET STEELS. B: — (f) the 

belly. (gg) the slots 

THE PALLET STONES, C and D:—(hh) 

8 


the impulse faces. (ii) the locking faces, 
(jj) the locking corners, (kk) the releas¬ 
ing corners. 

THE FORK. E: — (i) the slot (mm) the 
horns. 

THE ROLLER. G.— (n) the safety edge, 
(o) che passing hollow. 

Functions of the Escapement. 

* > \ 

We will now pursue in detail the func¬ 
tions of the escapement. Let us begin with 
the fork lying against the left banking and 
the balance making its excursion to the 



The roller pin enters the fork slot 
and coming in contact with it"? right side 
moves the fork, releasing an escape wheel 
tooth from the receiving stone. This brings 
the impulse faces of the teeth and the scone 
i'nto action. The tooth moves forward un¬ 
til released from the stone, and still for¬ 
ward until its motion is arrested by an¬ 
other tooth coming in contact with the 
locking face of the discharging stone. This 
space through which the tooth passes from 
the time of its release until arrested is 
THE DROP. The distance between the 
locking corner of the tooth and che lock¬ 
ing corner of the stone at the instant of 
drop is THE LOCK. At this instant the 
fork is a slight distance from the right 
hanking in reaclrng which the locking 
face of the stone slides down on the lock- 


9 


ing corner of the tooth. This is the 
SLIDE. 

The actions described above should be 
carefully noticed. This may, be done by 
moving the balance slowly while they are 
taking place, first on one stone then on the 
other. The locks on both stones should be 
equal as also the drop. The former should 
be about two one-hundredths of a milime- 
ter—approximately one one-thousandth of 
an inch; the drop should be 13 one-hun¬ 
dredths of a milimeter—about 5 one-chous* 
andths of an inch. The slide should about 
equal the lock. It is necessary that there 
be a certain amount of freedom between 
the roller pin and the sides of the fork 
slot. This should also be about one thous¬ 
andth inch This is to say, the fork slot 
should be that amount wider than the 
diameter of the pin. When the fork is rest¬ 
ing against a banking there should be a 
certain amount of freedom between the 
guard pin and safety edge of the roller. 
This should equal the slide. The pailet 
stones should be inclined at such an angle 
with relation to the escape wheel tooth 
that after a tooth drops on the locking face 
it will draw the stone down till the fork 
is stopped by a banking. This action is 
THE DRAFT. 

Upon the correct adjustment of chese 
actions depends the efficiency of the es¬ 
capement. Some of these actions can be 


10 


seen; others are hidden from view, but by 
the sense of touch can be determined with 
sufficient accuracy to produce good results 
The means for doing this we will describe 
further on. 


Lxamining an tscapement. 

In examining an escapement the first 
step should be to inspect the separate 
parts. See that all the pivots are in good 
condition; that the jewels and end stones 
are sound and properly fitted; that the 
edge of the roller is well polished and free 
from imperfections; that the roller jewel 
is perfectly polished, free from chips, 
firmly set, perfectly upright, and its face 
square to the front as shown in fig. 5. See 
that the sides of the fork slot are parallel 
and well finished; that the pallet stones are 
well polished, free from chips and firmly 
set. See that the escape wheel teeth are 
in good condition, free from burrs and im¬ 
perfections. Having seen chat every part 
is in suitable condition put the escape 
wheel and pallet in place and wind the 
mainspring about one turn. 

Holding the watch edgewise with the 
fork in a horizontal position try the drafc 
of each istone as follows. With a long 
pointed piece of pegwood press the fork 
away from the banking pin but not a suffi¬ 
cient distance to unlock the wheel. The 


11 


draft should be sufficiently scrong to draw 
the fork back against the banking when 
released. Should the draft be light there 
are two ways of correcting it. Sometimes 
the stone may be slightly tilted in the pal¬ 
let steel; or, drawing out the receiving 
stone and pushing in the discharging stone 
will increase the draft on both stones. 
These alterations in common with almost 
all other alterations made on pallets pro¬ 
duce more than one effect, necessitating 
careful observation and the exercise of 
judgment. The matter will be gone into 
more fully as we proceed. Now put in the 
balance. Try the lock by rotating it slowi¬ 
ly till an escape tooth drops on one stone; 
then try rhe other in the same manner. 
The locks should be equal on both. Draw¬ 
ing out either stone increases the locks 
on both; pushing in decreases it. Now 
notice how the impulse faces of the escape 
teeth pass across the pallet stones. See 
fig. 6. A is what I shall term correct di¬ 
vergence. B incorrect divergence. The es¬ 
cape wheel tooth in commencing its im¬ 
pulse contacts with the impulse face of 
the scone only at the locking corner of 
the tooth. In the incorrect way the locking 
corner of the stone contacts with the im¬ 
pulse face of the tooch which produces a 
scraping action and is liable to cut the face 
of the escape wheel tooth. The following 
rules should be observed in making alter¬ 
ations on the escape and pallet action. A 


reference to figures 1, 2, 3 and f> will ex¬ 
plain 'the conditions in connection with 
these rules. 

Drawing out either stone increases the 
lock on both. Drawing out the receiving 
stone increases the drop on the discharging 
stone; see Pig. 1. Drawing out the dis¬ 

charging stone increases the drop on the 
receiving; see Fig. 2. Drawing out the 

receiving stone will increase the impulse 
divergence on that stone as shown at A 
Fig. 6. Pushing in the discharging stone 
will have the same effect upon that stone 
and vice versa. Drawing ouc the receiving 
stone will increase the draft on the dis¬ 
charging stone and drawing out the dis¬ 
charging stone will decrease the draft on 

the receiving stone. Pushing in, of course, 
has the opposite effect. This statement may 
seem a little contradictory and it may be 
somewhat difficult to understand why 
drawing out either stone should alter the 
draft on the other. A reference to Fig. 
3 will make it clear. This diagram shows 
the wheel just released from the discharg¬ 
ing stone. We find that while drawing the 
receiving scone out brings a different part 
of its locking face into the path of the 
wheel tooth yet the point of intersection in 
that path remains precisely as before, con¬ 
sequently the drop on that stone remains 
unchanged, while it causes the tooth to 
drop farther up on the dischargingstone thus 

13 


striking it at a point which makes a greater 
angle with a line tangen'cal to a circle 
whose center is the pallet arbor and cir¬ 
cumference that point. If we hold the pal¬ 
let firmly in the position shown by the full 
lines and draw out the receiving scone as 
represented by the broken lines we shall 
have made no change whatever in the 
position of the escape wheel. It will have 
moved neither forward nor backward. We 
have however, drawn the receiving stone 
into such a position that before it can un¬ 
lock the wheel tooth it must move through 
an angle which as shown in fig. 1 increases 
the drop on the discharging. It will be also 
noticed that when the tooth strikes the 
locking face of the discharging stone the 
angle as compared with that represented 
by the full lines is increased. A careful 
study of the above explanations will enable 
the workman to secure the best obtainable 
results in the escape wheel and pallet ac¬ 
tion. It remains to secure like results in 
the fork and, roller action. 

Try the roller for truth in round. To do 
this set either one of the bankings so that 
there shall be a very slight shake between 
the guardpin and roller edge. Rotate the 
balance about one revolution, a little at a 
time, crying the shake at each point. 
Should it be unequal it is an indication 
that the roller is out of true in the round, 
a defect for which there is no remedy ex¬ 
cept a new roller. Now try the shake of 

14 


the roller pin in the fork slot which can 
be done by bringing- the jewel pin in line 
between the balance staff and pallet arbor 
and while holding the balance in this posi¬ 
tion grasp the fork with a light pair of 
tweezers and try the shake. As has been 
stated it should be about one thousandth 
of an inch or two and one-half hundredths 
of a miiemeter. Should it be too great or 
too little it is obvious that the pin must 
be changed. Now sec the bankings so 
that the fork will be arrested at the in¬ 
stant the wheel drops on each stone. This 
is called BANKED TO DROP In this con¬ 
dition the jewel pin should just clear the 
fork horns at both sides. Should it be 
found to clear at one side and not at the 
other the condition is what is called OUT 
OP ANGLE. In this case bend the fork; 
or swing it on the pallet steels if the parts 
are separate; toward the side that does not 
pass out and repeat this until its action 
shall be equal. It may result in not pass¬ 
ing out at either side. This indicates that 
the roller pin is too far forward. There is 
generally provided sufflcienc freedom in the 
hole in the roller for this pin so that it can 
be moved to a slight extent forward or 
back Should the pin be too far back it 
can be determined as follows;—Move the 
balance slowly bringing the roller pin into 
the fork slot; should the escapement un¬ 
lock before the pin is embraced by both 
sides of the islot it indicates that the pin 
is too far back. 


15 


To try the correct position of the guard 
pin proceed as follows: Bank the watch to 
drop, this is, to say, turn the bankings iso 
that they will arrest the fork at the in¬ 
stant the drop takes place. In this condi¬ 
tion the roller edge should just pass the 
guardpin without shake. Should there be 
shake ic indicates that the pin is too far 
back. This defect may generally be rem¬ 
edied by removing the pin, broaching the 

hole out slightly and inserting a larger one. 
If the guard pin will not allow the roller to 
pas^ it indicates that the pin is too far for¬ 
ward in which case the best way is to sub¬ 
stitute a roller smaller in diameter. If this 
is not convenient che pin may be carefully 
cut back until the desired result is obtain¬ 
ed. When this adjustment is properly se¬ 
cured it only remains to open the bank¬ 
ings to give the escapement the necessary 
slide which, as has been explained, should 
be about the same amount as the lock. 
This is to say the lock should be half the 
amount of lock and slide combined. 

The foregoing refers to the single roller 
escapement, that being in general use at 
the present time. The same rules apply to 
the double roller escapement. 

It is the desire of the SOUTH BEND 
WATCH COMPANY to give all needed in¬ 
formation on the subject of this pamphlet 
and realizing that the lever escapement 
involves many deep problems, our friend 
the watch maker is earnest’y invited to 
communicate with us in case any further 
information is desired, and has the assur¬ 
ance that his correspondence will be taken 
care of and meet with every attention on 
our part. 


1 <> 















































LIBRARY OF CONGRESS 



0 017 107 390 ft g 


When you have read this little booklet 
from cover to cover, by passing it to 
your watch-maker, it might be to your 
mutual advantage. 

















